In this courtroom sketch, Dias Kadyrbayev testifies in federal court on June 2 in Boston. / Jane Flavell Collins, AP

by G. Jeffrey MacDonald, USATODAY

by G. Jeffrey MacDonald, USATODAY

BOSTON - A five-day hearing that wrapped up Tuesday will determine whether potentially self-incriminating statements made by Dias Kadyrbayev, a friend of the Boston Marathon bombing suspect, will be admitted at Kadyrbayev's Sept. 8 trial.

No ruling was issued Tuesday, but the hearing did provide insights into the lives of the Russian-speaking, pot-smoking college students who comprised bombing suspect Dzhokhar Tsarnaev's close circle of friends.

Kadyrbayev, the 20-year-old Kazakh national facing up to 25 years in prison on obstruction of justice charges, testified Tuesday that he had suspected his friend was behind the April 15, 2013, bombings that left three dead and more than 260 injured.

That's why he allegedly disposed of Tsarnaev's backpack, which contained fireworks emptied of their explosive powder.

"You suspected he was the bomber, correct?" Assistant U.S. Attorney Stephanie Siegmann asked.

"Correct," Kadrybayev said.

Kadyrbayev did not say what, if anything, he knew about Tsarnaev's activities and potential motives in the run-up to the bombings. But because Kadyrbayev faces criminal charges of his own, the world might never find out.

"He has a Fifth Amendment privilege against self-incrimination," said David Frank, editor of Massachusetts Lawyers Weekly, which covers local legal affairs. "I would be extremely surprised if the day ever came when he would be on the witness stand testifying in the Tsarnaev trial."

After the hearing, Kadyrbayev attorney Robert Stahl said it's too soon to surmise what he knew about Tsarnaev's activities.

"I think you have to wait to hear the complete evidence about that before anything is concluded," Stahl said. "There's a lot more to come."

Kadyrbayev's comments came as prosecutors questioned his claims that he didn't understand his rights before talking with FBI agents for more than four hours on the day Tsarnaev was captured. On the stand, he answered questions about his life in the United States and about documents he signed regarding his rights.

What surfaced was a picture of Kadyrbayev's life as a partying teenager and small-time drug dealer who drove a BMW, sold marijuana to friends, seldom attended class and paid people to deceive his mother about how he was doing in school. He told FBI agents he planned to smoke pot soon after their questioning was finished.

In redirect examination, he expressed regret for some of his past behavior.

"You lied to your mom. Is that something you are proud about?" Stahl asked.

"No. I'm ashamed," Kadyrbayev answered.

For Kadyrbayev, the hearings are now finished because Judge Douglas Woodlock denied a motion to extend them. Stahl had sought to question state troopers on whether they failed to tell Kadyrbayev about an attorney who was trying to contact him during his FBI questioning. But Woodlock said no.

"The federal law on this issue is pretty clear: The defendant has to initiate the request for an attorney," Woodlock said. "He didn't."

When Woodlock rules in August on the motion to exempt Kadyrbayev's initial statements from the pool of evidence, the judgment will send a signal about how the court views the massive bombing investigation and manhunt that brought Boston to a standstill.

"This is the first time that judge will weigh in on the constitutionality of law enforcement conduct" in the investigation, Frank said. Regarding Kadyrbayev's initial statements, "the judge is going to have to decide if these are the kind of statements that pass legal muster."

Two other friends of Tsarnaev's also have trials coming up for their alleged roles in interfering with the investigation. Azamat Tazhayakov will be tried June 30. Robel Phillipos will be tried Sept. 29.

Tsarnaev is scheduled for trial on 30 counts on Nov. 3. If convicted, he could receive the death penalty.